Can Article 50 be reversed?

French President Emmanuel Macron escorts Britain's Prime Minister Theresa May as they arrive to speak to the press at the Elysee Palace in Paris, France on June 13, 2017.REUTERS/Philippe WojazerKey European figures this week dropped the biggest hints yet that the European Union would allow Britain to delay or cancel Brexit altogether by reversing Article 50 of the Lisbon Treaty.

He even said that once Brexit talks start "we need to be collectively clear that it's more difficult to reverse course."

Theresa May cancelling Brexit remains an unimaginable scenario given the outrage it would trigger and damage it would do the public's trust both in the Conservative Party and British democracy as a whole. But with the UK without a government at this time of writing and a second general election later this year a distinct possibility, it's clear that Britain is in not in an ideal state to enter such a defining set of negotiations in just a few days' time.

With this in mind, it is worth revisiting the question of what the law says about whether Prime Minister May or any other prime minister could actually reverse Brexit.

What is Article 50?

Article 50 is the official mechanism that allows a country to leave the EU and outlines a vague procedure for doing so. It was created as part of the Lisbon Treaty in 2009. Once Article 50 is triggered, the departing member state has two years to negotiate the terms of its exit from the EU. May invoked Article 50 on March 29, 2017.

What does the law say about reversing it?

There is no clear legal position on whether Britain could legally reverse Article 50 of the Lisbon Treaty. In fact, politicians and courts in Europe are split on the question.

Most recently, a leaked European Parliament draft resolution has said that the UK will be able to revoke Article 50 before it expires if the rest of the EU agrees. This means May would be able to reverse the two-year process prior to it coming to an end, as long as it was accepted by the remaining 27 EU member states.

Here's who else says Article 50 is revocable:

Lord Kerr, the author of Article 50, says "you can change your mind while the process is going on." He told the BBC: "During that [two-year] period, if a country were to decide actually we don't want to leave after all, everybody would be very cross about it being a waste of time ... They might try to extract a political price but legally they couldn't insist that you leave."

Speaking in the House of Lords in March, Kerr added: "When the government says as a matter of policy that they will not withdraw the notification ... they implicitly confirm that in law they could withdraw it and they could. It is revocable."

European Council President Donald Tusk suggested last year that Britain could change its mind. "In my opinion, the only real alternative to a 'hard Brexit' is 'no Brexit'," he said last October, adding that once exit discussions were over Britain must "assess the outcome of the negotiations and determine if Brexit is really in their interest."

On the other hand, here's who has suggested that Article 50 is irrevocable.

Justice Secretary Liz Truss has said, "my understanding is that it is irrevocable." She made the claim on "The Andrew Marr Show." The official position of the government is that it would never undo its decision.

The UK Supreme Court, in its decision requiring the House of Commons to vote on a bill triggering Article 50, said, "In these proceedings, it is common ground that notice under Article 50(2) (which we shall call 'Notice') cannot be given in qualified or conditional terms and that, once given, it cannot be withdrawn." That, however, was merely a procedural assumption in the case. The court did not rule on the merits of the position. As a matter of law it remains undecided.

In summary, the question of whether Britain could reverse Article 50 remains up for legal debate — but it clearly can't be ruled out. After all, conventional wisdom pointed to both Remain winning last year's in-out referendum and May returning a comfortable majority at last week's general election. Conventional wisdom isn't always correct.